Friday, January 25, 2013

Settled science: New paper finds where winds come from

A paper published today in Atmospheric Chemistry and Physics finds that condensation and evaporation merit attention as major, if previously overlooked, factors in driving atmospheric dynamics [including winds]. The paper finds, "The water vapor delivered to the atmosphere via evaporation represents a store of potential energy available to accelerate air and thus drive winds."Obviously, these "major" & "previously overlooked" factors have not been incorporated in climate models, and join the expanding list of major deficiencies of climate models, including internal waves, ocean oscillations, solar amplifying mechanisms, clouds, etc., etc.

A. M. Makarieva1,2, V. G. Gorshkov1,2, D. Sheil3,4,5, A. D. Nobre6,7, and B.-L. Li21Theoretical Physics Division, Petersburg Nuclear Physics Institute, 188300, Gatchina, St. Petersburg, Russia2XIEG-UCR International Center for Arid Land Ecology, University of California, Riverside, CA 92521, USA3School of Environment, Science and Engineering, Southern Cross University, P.O. Box 157, Lismore, NSW 2480, Australia4Institute of Tropical Forest Conservation, Mbarara University of Science and Technology, Kabale, Uganda5Center for International Forestry Research, P.O. Box 0113 BOCBD, Bogor 16000, Indonesia6Centro de Ciência do Sistema Terrestre INPE, São José dos Campos SP 12227-010, Brazil7Instituto Nacional de Pesquisas da Amazônia, Manaus AM 69060-001, BrazilAbstract. Phase transitions of atmospheric water play a ubiquitous role in the Earth's climate system, but their direct impact on atmospheric dynamics has escaped wide attention. Here we examine and advance a theory as to how condensation influences atmospheric pressure through the mass removal of water from the gas phase with a simultaneous account of the latent heat release. Building from fundamental physical principles we show that condensation is associated with a decline in air pressure in the lower atmosphere. This decline occurs up to a certain height, which ranges from 3 to 4 km for surface temperatures from 10 to 30 °C. We then estimate the horizontal pressure differences associated with water vapor condensation and find that these are comparable in magnitude with the pressure differences driving observed circulation patterns. The water vapor delivered to the atmosphere via evaporation represents a store of potential energy available to accelerate air and thus drive winds. Our estimates suggest that the global mean power at which this potential energy is released by condensation is around one per cent of the global solar power – this is similar to the known stationary dissipative power of general atmospheric circulation. We conclude that condensation and evaporation merit attention as major, if previously overlooked, factors in driving atmospheric dynamics.